gonzales-pe
Advanced tools
The gonzales-pe npm package is a CSS parser that can parse CSS, SCSS, LESS, and other CSS-like syntaxes. It is useful for tasks such as linting, formatting, and transforming stylesheets.
Parsing CSS
This feature allows you to parse CSS code into an Abstract Syntax Tree (AST). The code sample demonstrates how to parse a simple CSS string and convert it into a JSON representation of the AST.
const gonzales = require('gonzales-pe');
const ast = gonzales.parse('.class { color: red; }', { syntax: 'css' });
console.log(ast.toJson());Parsing SCSS
This feature allows you to parse SCSS code into an AST. The code sample shows how to parse a simple SCSS string and convert it into a JSON representation of the AST.
const gonzales = require('gonzales-pe');
const ast = gonzales.parse('.class { color: red; }', { syntax: 'scss' });
console.log(ast.toJson());Parsing LESS
This feature allows you to parse LESS code into an AST. The code sample demonstrates how to parse a simple LESS string and convert it into a JSON representation of the AST.
const gonzales = require('gonzales-pe');
const ast = gonzales.parse('.class { color: red; }', { syntax: 'less' });
console.log(ast.toJson());Transforming AST
This feature allows you to traverse and transform the AST. The code sample shows how to change the color property from 'red' to 'blue' in a CSS AST.
const gonzales = require('gonzales-pe');
let ast = gonzales.parse('.class { color: red; }', { syntax: 'css' });
ast.traverse(function(node) {
if (node.type === 'declaration' && node.content[0].content === 'color') {
node.content[1].content = 'blue';
}
});
console.log(ast.toString());PostCSS is a tool for transforming CSS with JavaScript plugins. It is more versatile and has a larger ecosystem of plugins compared to gonzales-pe. PostCSS can be used for linting, autoprefixing, and many other CSS transformations.
CSSTree is a tool for working with CSS, including parsing, generating, and analyzing CSS. It provides a more detailed and accurate AST compared to gonzales-pe and includes utilities for working with the AST.
Rework is a plugin framework for CSS preprocessing. It allows you to transform CSS with plugins, similar to PostCSS. Rework is simpler and less feature-rich compared to PostCSS but can be easier to use for basic transformations.
Gonzales PE is a CSS parser which plays nicely with preprocessors.
Currently those are supported: SCSS, Sass, LESS.
Try out Gonzales PE online: Gonzales PE Playground.
(1) To install command-line tool globally:
npm install -g git://github.com/tonyganch/gonzales-pe.git#dev
(2) To install parser as a project dependency:
npm install --save git://github.com/tonyganch/gonzales-pe.git#dev
(3) If for some reason you want to build files yourself:
# Clone the repo.
git clone git@github.com:tonyganch/gonzales-pe.git
# Go to dev branch.
git checkout dev
# Install project dependencies.
npm install
# Install git hooks and build files.
npm run init
Basically there are a few things you can do:
The different type of tree nodes can be found in docs/node-types.md.
In examples below I assume that gonzales is a parser module and parseTree
is some parsed css:
let gonzales = require('gonzales-pe');
let parseTree = gonzales.parse(css);
Creates a new node. Useful when you need to add something to a tree.
| {Object} | options | Options to pass to a `Node` constructor. |
| {Object} | A new node. |
let css = 'a {color: tomato}';
let parseTree = gonzales.parse(css);
let node = gonzales.createNode({ type: 'animal', content: 'panda' });
parseTree.content.push(node);
Parses a css string.
| {string} | css | A string to parse. |
| {Object=} | options | Optional. Additional options:
|
| {Object} | Parse tree. |
let css = 'a {color: tomato}';
let parseTree = gonzales.parse(css);
let less = 'a {$color: tomato}';
let parseTree = gonzales.parse(less, {syntax: 'less'});
let less = '$color: tomato';
let parseTree = gonzales.parse(less, {syntax: 'less', rule: 'declaration'});
Checks whether there is a child node of given type.
| {string} | type | Node type we're looking for. For a list of available values see "Node types". |
| {boolean} |
true if a tree contains a child node of a given type,
false otherwise.
|
if (parseTree.contains('space')) {
doSomething();
}
| {string|Array} | Node's content (child nodes or a string). |
Calls a function for every child node in tree. If type parameter is passed,
calls a function only for child nodes of a given type. The main difference from
parseTree.forEach() is that this method loops through node list from the end
to beginning.
| {string=} | type | Optional. A node type by which to filter child nodes before applying a callback function. For a list of available values see "Node types". |
| {Function} | callback |
Function to call for every child node. Accepts following parameters:
|
parseTree.eachFor(function(childNode) {
doSomething(childNode);
});
// Remove all child spaces.
parseTree.eachFor('space', function(spaceNode, i) {
parseTree.removeChild(i);
});
| {Object} |
End position of the node. Contains following info:
|
Gets the first child node. If type parameter is passed, gets the first child
node of a given type. If no node has been found, returns null.
| {string=} | type | Optional. Node type to look for. For a list of available values see "Node types". |
| {?Object} | A node. |
let node = parseTree.first();
node.content = 'panda';
let node = parseTree.first('multilineComment');
node.content = 'panda';
Calls a function for every child node in tree. If type parameter is passed,
calls a function only for child nodes of a given type. The main difference from
parseTree.eachFor() is that this method loops through node list from the
beginnig to end.
| {string=} | type | Optional. A node type by which to filter child nodes before applying a callback function. For a list of available values see "Node types". |
| {Function} | callback |
Function to call for every child node. Accepts following parameters:
|
parseTree.forEach(function(childNode) {
doSomething();
});
parseTree.forEach('space', function(spaceNode) {
doSomething();
});
Gets nth child of the parseTree. If no node has been found, returns null.
| {number} | index | Index number of node which we're looking for. |
| {?Object} | A node. |
var node = parseTree.get(2);
doSomething(node);
Inserts a node to a given position in parseTree.
| {number} | index | Index of position where to insert the node. |
| {Object} | node | A node to insert. |
let node = gonzales.createNode({type: 'animal', content: 'panda'});
parseTree.insert(2, node);
Checks whether the node is of given type.
| {string} | type |
A node type against which to check type of parseTree.
For a list of available values see
"Node types".
|
| {boolean} |
true if types are equal, false otherwise.
|
if (node.is('space')) {
node.content = '';
}
Gets the last child node. If type parameter is passed, gets the last child
node of a given type. If no node has been found, returns null.
| {string=} | type | Optional. Node type to look for. For a list of available values see "Node types". |
| {?Object} | A node. |
let node = parseTree.last();
node.content = 'panda';
let node = parseTree.last('multilineComment');
node.content = 'panda';
| {number} | Number of child nodes. |
Removes a child node at a given position.
| {number} | index | Index of a child node we need to remove. |
| {Object} | Removed node. |
// Swap nodes.
var node = parseTree.removeChild(1);
parseTree.insert(0, node);
| {Object} |
Start position of the node. Contains following info:
|
| {string} | Syntax of original parsed string. |
Converts parse tree to JSON. Useful for printing.
| {Object} | Parse tree in JSON |
Converts parse tree back to string according to original syntax.
| {string} | A compiled string. |
let css = parseTree.toString();
Calls the function for every node in a tree including parseTree itself.
| {Function} | callback |
Function to apply to every node. Accepts following parameters:
|
parseTree.traverse(function(node, index, parent) {
if (node.is('multilineComment')) {
parent.removeChild(index);
} else if (node.is('space')) {
node.content = ' ';
}
});
This method should be called for a root node, because calling it for a child
will be more time consuming.
Calls the function for every node of a given type. This means not just child
nodes, but grandchilds and so on.
| {string} | type | Node type. For a list of available values please see "Node types". |
| {Function} | callback |
Function to apply to every node of a given type.
Accepts following parameters:
|
// Remove all comments.
parseTree.traverseByType('multilineComment', function(node, index, parent) {
parent.removeChild(index);
});
This method should be called for a root node, because calling it for a child
will be more time consuming.
Calls the function for every node of given types. This means not just child
nodes, but grandchilds and so on.
| {Array.string} | types | List of node types. For a list of available values please see "Node types". |
| {Function} | callback |
Function to apply to every node of given types.
Accepts following parameters:
|
// Remove all comments and spaces.
let types = ['multilineComment', 'space'];
parseTree.traverseByTypes(types, function(node, index, parent) {
parent.removeChild(index);
});
| {string} | Node type. For a list of available values see "Node types". |
To run tests:
npm test
This command will build library files from sources and run tests on all files in syntax directories.
Every test has 3 files: source stylesheet, expected parse tree and expected string compiled back from parse tree to css.
If some tests fail, you can find information in test logs:
log/test.log contains all information from stdout;log/expected.txt contains only expected text;log/result.txt contains only result text.The last two are made for your convenience: you can use any diff app to see the defference between them.
If you want to test one specific string or get a general idea of how Gonzales
works, you can use test/ast.js file.
Simply change the first two strings (css and syntax vars) and run:
node test/single-test.js
If you find a bug or want to add a feature, welcome to Issues.
If you are shy but have a question, feel free to drop me a line.
FAQs
Gonzales Preprocessor Edition (fast CSS parser)
The npm package gonzales-pe receives a total of 1,307,692 weekly downloads. As such, gonzales-pe popularity was classified as popular.
We found that gonzales-pe demonstrated a not healthy version release cadence and project activity because the last version was released a year ago. It has 1 open source maintainer collaborating on the project.
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